I’m with Overgeeked on this one. It can be much harder to ‘just have a serious conversation with’ or ‘kick to the cub’ someone who is a long time friend or someone’s partner.
Players who optimize usually have no problem spamming such effective tactics. While I as a DM have no desire to spam a solution. I’m trying to facilitate interesting experiences and spamming anything is anathema to that. Sure one encounter in 5 or 6 might have an area of effect that ignores an obscenely high AC. However I don’t want to exclude 70% of creatures in a game by focusing on these.
There are 7 defences in 5e. AC is one of them.
At lower levels, AC targetting attacks are more common. Making them become less common is reasonable, and it doesn't have to be AOEs.
...
Ignoring 70% of the creatures in the game is a strange statement. You are the DM. You determine what creatures are in the game. You determine their stats. The MM provides a buffet of options.
Ie, that giant requires a dex save, deals 1d6*10 minus your AC damage per hit; no armor can block the swing it can only reduce the damage of the blow. You
have to dodge it.
This isn't ignoring armor, but doesn't make AC a veto on being hit.
It has also been suggested that a way round a high AC is to target other players. This has the effect of rewarding the optimizer who gains even thicker plot armour as enemies divert around them like a train’s snow plough. Targeting PCs that haven’t optimized. This is unsatisfactory for me.
Someone with infinite AC who isn't attacked until the battle is lost has failed at optimization.
If there are 7 attackers, and 3 go after the super-tank and the other 4 attack those who aren't super-tanks, then both the super-tank gets to laugh at the attacks missing them,
and there is peril for everyone.
The tactical problem, of how to force more foes to attack the super tank, becomes an interesting shared one.
Yes, this "rewards" the optimizer, in that they get to laugh at attacks missing them. But the game remains interesting and fun, so who cares?
I guess the problem is, some other PC has the image "I am tough" and looks weak compared to the optimizer.
Indestructible optimization often rely on specific techniques, much like Smash optimization does. As a DM, if you find the gap is too large, you can fix it.
There was the shield I wrote that lets you spend a reaction to halve damage from an attack. If the problem is AC instead, items that let you expend your reaction for a +3 bonus to AC (or even +5 against one attack, resistance if it still hits) compete with the reaction slot; so such an item is only useful to the non-optimizers. At the same time, it means that you have reduced the AC gap in your party.
And with reduced AC gap... adding +3 to every monsters ATK makes the optimizer hittable, and the AC gap reduction work made the other PCs still missable.
You don't have to just add +3 to every monster's ATK, but you
can. You can instead give reasons why there is a +3 bonus to ATK. Boost the monsters you use attack stat by +6, for example. Give them magic weapons (so long as you don't use a fixed magic item price chart and they are weaker than PC weapons, this has near zero balance impact), steroid potions (with nasty side effects, so PCs don't abuse them).
It is not satisfying to feel overshadowed. There is a big difference between what a character using an action, bonus action, multiple attacks and a reaction can do in a round vs a character that casts one spell or makes one attack. A big part of optimization involves making all these options hit hard. We know there can be problems with sentinel, polearm mastery, shield spells, some of the battlemaster techniques. Now it has also been suggested that multiclassing or feats be banned. Stopping everyone to else using things that are fun because some people combine them in the most efficient way possible and then spam that is not satisfactory either.
So, you have identified resources that the optimizer uses.
To repeat myself, provide uses for those resources that are not as good as the optimizers uses in the form of magic items or houserules.
Then turn up the game difficulty to match.
One player has PAM+GWM+BM reaction attacks at level 11, to make 5 attacks/round at +10 to damage with their +2 glaive? Neat. That is a lot of damage. The 16 dex ranger dual wielding short swords isn't going to keep up with that.
Flamedancers: This pair of +2 scimitars deals +1d6 fire damage on a hit. When you have both equipped and use two weapon fighting, your bonus action attack lets you attack twice. When you are hit by an attack you can expend a reaction to attack back; if your reaction attack hits, the triggering attack must reroll with disadvantage.
If I did my math right, this still does less damage than the BM PAM GWM fighter does, but it (a) closes the gap, and (b) is really fun.
As the DM you have mechanical levers. They aren't the only things you have, but they are part of your toolkit.
You are in charge of magic items. You are in charge of monster stats.
Part of the DM's job is to use those levers.
This might be "show favitorism", but you can give similar customized items out for the PAM fighter.
Glaive of Lost Souls: This +2 Glaive is imbued with the souls of those it kills. Whenever you damage a creature, you gain 5 temporary HP; if the blow killed the creature, you also gain temporary HP equal to 1/10s of the creatures max HP on top of that. As a reaction when you reduce a creature to 0 HP, you can cast Soul Cage without components to capture the soul of the creature. You can only cast Soul Cage this way once before completing a long rest.
You'll note that this Glaive is super cool and strong, but
doesn't boost the thing the optimizer has already boosted.
PPS. The shield of faith can be cast as a bonus action and lasts all combat.
@Horwath it doesn’t need to be used in every encounter, only needs to be used where the enemy is tougher or in big numbers. Enemies already struggle to hit AC 20+. The same applies for
shield. You only need to use it in the 5-10% of hits that penetrate regular AC. This kind of Plan B casting where protection comes at little action economy cost and can be used as needed is extremely efficient (and optimized).
Honestly, shield is enough of a problem that I have houseruled it. Shield on a non-low-AC caster breaks bounded accuracy, and getting enough slots to keep it up 100% of the time isn't hard if you can make a full caster with a high-AC kit.
The problem is less the +5 than the "until the end of your next turn" part of it.
PPS. Really disappointed to see how personal things got at Overgeeked for sharing an opinion... particularly one that while debatable, isn’t extreme or even unusual. Seeing the reactions to my apparently ‘weak’ example of high AC, I can understand them not wanting to give their own adding fuel to the fire.
Overgeeked has been using loaded language to treat people who like the optimization mini-game as bad people.
When your opinion is "that is bad wrong fun, how do I stop them", yes, people who like that fun may treat it personally.
When it is pointed out that it isn't bad wrong fun, Overgeeked has doubled down and continued to insult people who like doing optimization and seeing it in actual play.
Badwrongfun results in negative responses.